Defensive strategies are used by incumbent firms to discourage potential competitors from entering their industry. There are pre-entry strategies like signaling and fortifying defenses, as well as post-entry strategies. Signaling involves announcing the intent to retaliate against any competitor attacks. Fortifying defenses strengthens barriers to entry through economies of scale, product differentiation, and proprietary advantages. Post-entry strategies include continuous improvement to stay ahead of competitors, capacity expansion to utilize excess capacity, and introducing fighting brands to combat threats to the core brand.